Instant consumption means the consumption of fuel when your driving, when in rest it could not compute the consumption as KM travel is zero. Another thing while driving press clutch and it will show you IC as 50km/lt.

Instant Consumption is a great way to keep a check on the mileage of the car. Select it and try keeping it to 20-25kmph most of the time by rolling the car after acceleration. This is give you a fair idea of how to maximise your mileage in terms of your driving habits. Flooring the race-pedal will bring it to 1-2 kmpl and if the car rolls it can go upto a max. of 50kmpl:drinks
So if someone keeps the figures between 20-25 kmpl during 60-70% of driving, he/she will be happy with the mileage. And he/she will develop a sober driving style too(no jump-start, no sudden braking, no racing or overtaking etc).